Submission #1035669

#	Time	Username	Problem	Language	Result	Execution time	Memory
1035669		vjudge1	Political Development (BOI17_politicaldevelopment)	C++17	100 / 100	564 ms	335340 KiB

politicaldevelopment

#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector,fast-math,inline")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,lzcnt,mmx,abm,avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;

#define all(x) x.begin(), x.end()

const int N = 5e4;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n, k, c, ans;
vector<int> vt, adj[N];
set<int> st[N];
bitset<N> bt[N], r, toTake;

void clean(int x) {
  for (int i = 0; i < n; i++) {
    if (adj[i].size()+1 < x) r[i] = 1;
  }
}

void dfs(int x) {
  c++;
  if (c > ans) {
    ans = c;
    clean(c+1);
  }

  vector<int> opt;
  for (int y = toTake._Find_first(); y < n; y = toTake._Find_next(y)) { 
    if (r[y]) continue;

    opt.push_back(y);
  }

  int sz = opt.size();
  if (!sz) return;

  int y = opt[rng() % sz];

  toTake &= bt[y];
  dfs(y);
}

signed main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);

  cin >> n >> k;
  for (int i = 0; i < n; i++) {
    int x; cin >> x;

    for (int j = 0; j < x; j++) {
      int y; cin >> y;
      st[i].insert(y);

      if (st[y].find(i) != st[y].end()) {
        bt[i][y] = 1;
        adj[i].push_back(y);

        bt[y][i] = 1;
        adj[y].push_back(i);
      }
    }
  }

  ans = 1;
  for (int i = 0; i < n*3; i++) {
    c = 0;
    toTake = bt[i%n];
    dfs(i%n);
  }

  cout << ans << "\n";
}

Compilation message (stderr)

politicaldevelopment.cpp: In function 'void clean(int)':
politicaldevelopment.cpp:19:25: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   19 |     if (adj[i].size()+1 < x) r[i] = 1;
      |         ~~~~~~~~~~~~~~~~^~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 23 / 23
• Subtask 4: 38 / 38
• Subtask 5: 23 / 23